Transmitter/Receiver:

Used in churches, arenas, classrooms, home theaters, etc.

An audio source is transmitted to a receiver via infrared signals, radio frequency, etc. Depending on the system, you will either need to use headphones, a telecoil accessory (such as a neckloop or silhouette), an audio cable, or a wireless ear-level receiver.

This setup is commonly applies to FM systems, which are useful in a variety of situations such as a classroom lecture, in a restaurant or a sales meeting.

Bluetooth Device:

Bluetooth is a low-power, short range technology that wirelessly connects cell phones (or MP3 devices, PDAs, computers, etc.) to a compatible receiver. Some receivers can be connected directly to the audio processor and others are used with a headset or telecoil accessory.